H. A. Sarvetnick, "Plastisols and Organosols", Van Nostrand Reinhold Company, New York (1972), describes plastisols as fluid mixtures, ranging in viscosity from pourable liquids to heavy pastes, obtained by dispersing polymeric resin particles in nonvolatile, nonaqueous liquid plasticizers, i.e., materials which are compatible with the polymer or resin and increase its workability and flexibility but are not solvents for the resin or polymer under ordinary conditions of storage. When the plastisol has been formed into a desired shape, e.g., by molding or coating, it can be heated to coalesce the polymeric resin particles and the nonvolatile liquid constituent, thereby forming a homogeneous mass. Volatile diluents can be added to plastisol dispersions to modify their viscosity and to achieve desirable handling characteristics in coating or other forming operations. A dispersion that contains no more than 10% volatile diluent is regarded as a plastisol.
Polyvinyl chloride has been described in the literature as the primary polymer used in forming plastisols. Polyvinyl chloride plastisols have been described in U.S. Pat. No. 3,795,649 wherein the polyvinyl chloride is copolymerized with other monomers, including acrylic monomers, that constitute a minority (&lt;35%) of the polymer composition. In U.S. Pat. No. 2,618,621 there are disclosed polyvinyl chloride plastisols wherein part of the plasticizer content is replaced with an acrylic monomer, which is then conventionally thermally polymerized at the temperature encountered in the step of coalescing the polyvinyl chloride resin.
It has been found that polyvinyl chloride plastisol dispersions can be made photoactive by having attached to the backbone of the polyvinyl chloride polymer photopolymerizable or photocrosslinkable groups, such that upon exposure to actinic radiation, the modified polyvinyl chloride polymer becomes polymerized or crosslinked. Such photoactive plastisols, in element form, can be used in a process of image formation that may be a positive working washout imaging system or a negative toned imaging system.